Journal of Microbiology

Journal Article

Intervention with kimchi microbial community ameliorates obesity by regulating gut microbiota: Seong-Eun Park , Sun Jae Kwon , Kwang-Moon Cho , Seung-Ho Seo , Eun-Ju Kim , Tatsuya Unno , So-Hyeon Bok , Dae-Hun Park , Hong-Seok Son; J. Microbiol. 2020;58(10):859-867. Published online September 2, 2020; DOI: https://doi.org/10.1007/s12275-020-0266-2

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Abstract: The objective of this study was to evaluate anti-obesity effects of kimchi microbial community (KMC) on obesity and gut microbiota using a high fat diet-induced mouse model compared to effects of a single strain. Administration of KMC decreased body weight, adipose tissue, and liver weight gains. Relative content of Muribaculaceae in the gut of the KMCtreated group was higher than that in the high-fat diet (HFD) group whereas relative contents of Akkermansiaceae, Coriobacteriaceae, and Erysipelotrichaceae were lower in KMCtreated group. Metabolic profile of blood was found to change differently according to the administration of KMC and a single strain of Lactobacillus plantarum. Serum metabolites significantly increased in the HFD group but decreased in the KMC-treated group included arachidic acid, stearic acid, fumaric acid, and glucose, suggesting that the administration of KMC could influence energy metabolism. The main genus in KMC was not detected in guts of mice in KMC-treated group. Since the use of KMC has advantages in terms of safety, it has potential to improve gut microbial community for obese people.

Review

[Minireivew]Microbial consortia including methanotrophs: some benefits of living together: Rajendra Singh , Jaewon Ryu , Si Wouk Kim; J. Microbiol. 2019;57(11):939-952. Published online October 28, 2019; DOI: https://doi.org/10.1007/s12275-019-9328-8

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29 Citations

Abstract: With the progress of biotechnological research and improvements made in bioprocessing with pure cultures, microbial consortia have gained recognition for accomplishing biological processes with improved effectiveness. Microbes are indispensable tool in developing bioprocesses for the production of bioenergy and biochemicals while utilizing renewable resources due to technical, economic and environmental advantages. They communicate with specific cohorts in close proximity to promote metabolic cooperation. Use of positive microbial associations has been recognized widely, especially in food industries and bioremediation of toxic compounds and waste materials. Role of microbial associations in developing sustainable energy sources and substitutes for conventional fuels is highly promising with many commercial prospects. Detoxification of chemical contaminants sourced from domestic, agricultural and industrial wastes has also been achieved through microbial catalysis in pure and co-culture systems. Methanotrophs, the sole biological sink of greenhouse gas methane, catalyze the methane monooxygenasemediated oxidation of methane to methanol, a high energy density liquid and key platform chemical to produce commodity chemical compounds and their derivatives. Constructed microbial consortia have positive effects, such as improved biomass, biocatalytic potential, stability etc. In a methanotroph- heterotroph consortium, non-methanotrophs provide key nutrient factors and alleviate the toxicity from the culture. Non-methanotrophic organisms biologically stimulate the growth and activity of methanotrophs via production of growth stimulators. However, methanotrophs in association with cocultured microorganisms are in need of further exploration and thorough investigation to study their interaction mode and application with improved effectiveness.

Journal Articles

A novel methanotroph in the genus Methylomonas that contains a distinct clade of soluble methane monooxygenase: Ngoc-Loi Nguyen , Woon-Jong Yu , Hye-Young Yang , Jong-Geol Kim , Man-Young Jung , Soo-Je Park , Seong-Woon Roh , Sung-Keun Rhee; J. Microbiol. 2017;55(10):775-782. Published online September 28, 2017; DOI: https://doi.org/10.1007/s12275-017-7317-3

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Abstract: Aerobic methane oxidation is a key process in the global carbon cycle that acts as a major sink of methane. In this study, we describe a novel methanotroph designated EMGL16-1 that was isolated from a freshwater lake using the floating filter culture technique. Based on a phylogenetic analysis of 16S rRNA gene sequences, the isolate was found to be closely related to the genus Methylomonas in the family Methylococcaceae of the class Gammaproteobacteria with 94.2–97.4% 16S rRNA gene similarity to Methylomonas type strains. Comparison of chemotaxonomic and physiological properties further suggested that strain EMGL16-1 was taxonomically distinct from other species in the genus Methylomonas. The isolate was versatile in utilizing nitrogen sources such as molecular nitrogen, nitrate, nitrite, urea, and ammonium. The genes coding for subunit of the particulate form methane monooxygenase (pmoA), soluble methane monooxygenase (mmoX), and methanol dehydrogenase (mxaF) were detected in strain EMGL16-1. Phylogenetic analysis of mmoX indicated that mmoX of strain EMGL16-1 is distinct from those of other strains in the genus Methylomonas. This isolate probably represents a novel species in the genus. Our study provides new insights into the diversity of species in the genus Methylomonas and their environmental adaptations.

Metagenomic analysis reveals the contribution of anaerobic methanotroph-1b in the oxidation of methane at the Ulleung Basin, East Sea of Korea: Jin-Woo Lee , Kae Kyoung Kwon , Jang-Jun Bahk , Dong-Hun Lee , Hyun Sook Lee , Sung Gyun Kang , Jung-Hyun Lee; J. Microbiol. 2016;54(12):814-822. Published online November 26, 2016; DOI: https://doi.org/10.1007/s12275-016-6379-y

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Abstract: We have previously identified a sulfate methane transition zone (SMTZ) within the methane hydrate-bearing sediment in the Ulleung Basin, East Sea of Korea, and the presence of ANME-1b group in the sediment has been shown by phylogenetic analysis of a 16S rRNA gene. Herein, we describe taxonomic and functional profiling in the SMTZ sample by metagenomic analysis, comparing with that of surface sediment. Metagenomic sequences of 115 Mbp and 252 Mbp were obtained from SMTZ and surface sediments, respectively. The taxonomic profiling using BLASTX against the SEED within MG-RAST showed the prevalence of methanogens (19.1%), such as Methanosarcinales (12.0%) and Methanomicrobiales (4.1%) predominated within the SMTZ metagenome. A number of 185,200 SMTZ reads (38.9%) and 438,484 surface reads (62.5%) were assigned to functional categories, and methanogenesis-related reads were statistically significantly overrepresented in the SMTZ metagenome. However, the mapping analysis of metagenome reads to the reference genomes, most of the sequences of the SMTZ metagenome were mapped to ANME-1 draft genomes, rather than those of methanogens. Furthermore, the two copies of the methyl-coenzyme M reductase gene (mcrA) segments of the SMTZ metagenome were clustered with ANME-1b in the phylogenetic cluster. These results indicate that ANME- 1b reads were miss-annotated to methanogens due to limitation of database. Many of key genes necessary for reverse methanogenesis were present in the SMTZ metagenome, except for N5,N10-methenyl-H4MPT reductase (mer) and CoBCoM heterodisulfide reductase subunits D and E (hdrDE). These data suggest that the ANME-1b represents the primary player the anaerobic methane oxidation in the SMTZ, of the methane hydrate-bearing sediment at the Ulleung Basin, East Sea of Korea.

Research Support, Non-U.S. Gov't

Isolation and Taxonomic Characterization of a Novel Type I Methanotrophic Bacterium: Hee Gon Kim , Gui Hwan Han , Chi-Yong Eom , Si Wouk Kim; J. Microbiol. 2008;46(1):45-50.; DOI: https://doi.org/10.1007/s12275-008-0017-2

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Abstract: A methane-oxidizing bacterium was isolated from the effluent of manure and its molecular and biochemical properties were characterized. The isolate was aerobic, Gram-negative, and non-motile. The organism had a type I intracytoplasmic membrane structure and granular inclusion bodies. The outer cell wall surface (S-layers) was tightly packed with cup-shaped structures. Colonies were light yellow on nitrate mineral salt agar medium. In addition, the organism was catalase and oxidase positive. The isolate used the ribulose monophosphate (RuMP) pathway for carbon assimilation, and was able to utilize methane and methanol as a sole carbon and energy source, however, it could not utilize any other organic compounds that were tested. The cells grew well in a mixture of methane and air (methane:air=1:1, v/v) in a compulsory circulation diffusion system, and when grown under those conditions, the optimum pH was approximately 7.0 and the optimal temperature was 30°C. In addition, the specific growth rate and generation time were 0.13 per h and 5.43 h, respectively, when grown under the optimum conditions. The major ubiquinone was Q-8, and the G+C mol% of the DNA was 55.3. Phylogenetic analyses based on the 16S rRNA gene sequence comparisons showed that this bacterium belongs to a group of type I methanotrophs, and that it is most closely related to Methylomicrobium, with a sequence similarity of 99%. Therefore, the isolate was named Methylomicrobium sp. HG-1.

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